Nothing in this ticket or #23707 mentioned "margin" once. Both are caused by the fact that those post format combinations use the same background color (as the OPs mentioned in both).

There's three possible resolutions to this:

Add in additional post format colors so each have their own. There is a finite number of formats, so this really would be reasonable.

Add in some new border style. Doesn't matter what it looks like, could be solid line separator, a drop shadow, or whatever, just as long as it provides some indication that you're looking at the next post.

Leave it how it is. It's a rare circumstance in the first place, and this was how the theme was designed. It's a minor issue that's easily worked around in the post itself. Usually the post date after each link is the end of the post, without a full description of the link (like this screenshot​ - which really abuses the "link" post format for a regular post).

In all cases, this ticket is not just "related", it's a duplicate of #23707, where a decision was made to leave it. If you want to revisit that, the appropriate action is to re-open #23707, and discuss it there, especially since that also happens to be where sabreuse first reported that this was the case with the Link + Aside combination, and she deserves some follow-up to her comments on that ticket if anything actually does happen with this.